A Class 4 impact resistant shingle costs more than the standard version of its line, and the rating does not mean what most people think it means. Ask for both numbers on one estimate and ask your agent whether your policy credits the upgrade before you pick. The asphalt shingle page covers the base lines, colors, install, and prices; this is only the Class 4 decision.
What Class 4 impact resistant shingles are tested to survive, and what the Altoona hail was
UL 2218, the impact standard for asphalt shingles, is a drop test. Steel balls of 1.25, 1.5, 1.75, and 2 inches fall onto a shingle deck from 12 to 20 feet, heights matched to the energy a hailstone of that size carries. Class 4, the highest rating, is the two-inch ball from 20 feet; Class 3 is the 1.75-inch ball from 17 feet. Each spot is struck twice, then the shingle is turned over: any tear, crack, or rupture visible on the back is a failure. Crushed granules, dents, and openings visible only on the top are not. So the rating says a shingle did not crack through after two-inch hits, and nothing about the dents and granule loss an adjuster sees from the top. UL Solutions notes that gap, and IBHS, the Insurance Institute for Business and Home Safety, says dents and tears are the damage most tied to later leaks.
Now the Altoona question. The largest projectile in any shingle rating is two inches. Altoona took four in May 2025, as the hail versus wind damage guide records, and no standard rates a shingle for that. In IBHS’s cannon tests with 1.5-inch lab hail, every shingle, rated or unrated, scored Good or Excellent; two-inch stones are where the products separate. IBHS’s November 2025 round rated a record 24 impact resistant products, most Good, none Excellent. So a polymer-modified Class 4 shingle buys better odds against the inch-and-a-half to two-inch stone, and no promise about a repeat of Altoona.
Which GAF, Owens Corning, and CertainTeed shingles are actually Class 4
The base lines we install, Landmark, Timberline HDZ, and Duration, all sit at Class 3 on State Farm’s product listing, not Class 4. The rating belongs to a specific sibling in each line, and the wrapper has to say so.
| Line we install | Class 4 version | How it earns the rating | Wind warranty | State Farm, Sept 2026 |
|---|---|---|---|---|
| CertainTeed Landmark | Landmark ClimateFlex | Polymer-modified asphalt | 15 years at 110 mph, 160 mph upgrade available | Class 4 |
| GAF Timberline HDZ | Timberline AS II (ArmorShield II) | SBS-modified asphalt | WindProven, no wind speed limit, with four GAF accessories (starter strips, deck protection, ridge cap, leak barrier or attic ventilation) | Class 4 |
| Owens Corning Duration | Duration FLEX | SBS polymer-modified asphalt | 160 mph with Owens Corning components and starter strips | Class 4 |
| Owens Corning Duration | Duration STORM | Standard asphalt with a polymeric WeatherGuard backing | 160 mph, same conditions | Class 4 |
The third column matters most, because manufacturers reach Class 4 two ways: a mesh or scrim bonded to the back of an ordinary shingle, or a rubber-like polymer such as SBS blended into the asphalt. IBHS’s cannon work separates them: every impact resistant shingle that scored Good or Excellent at two inches was polymer-modified, and where a maker sold two, the one built on an older technology such as a scrim backing always scored below that maker’s own standard shingle. So the two Owens Corning options differ: STORM gets its rating from a backing, FLEX from the asphalt. We have not seen a published IBHS score for either Duration, so this is an inference from construction rather than a head-to-head result, but it favors FLEX. GAF also says AS II’s SBS asphalt lays flatter in cold than its standard shingle, which counts on an April or late-October roof near the 40°F line below which shingle makers call for hand sealing.
How the Wisconsin insurance credit for Class 4 shingles is claimed, and what voids it
State Farm publishes the most on its credit, and its discount list names 26 states, Wisconsin among them; three conditions run through its paperwork. First, the product: start with the current listing, revised September 1, 2026, at the class it gives each product, the last column of the table above. The listing says other qualifying products may exist, so if a bid names a shingle that is not on it, have the agent confirm it in writing first. Second, a certification: the installer signs that the listed product went over the entire roof, was not laid over existing roofing, and is free of defects or damage, hail damage included, and the form warns that an intentional misrepresentation is fraud. You send the signed form to your agent, and the agent tells you what credit, if any, your policy carries. Third, asphalt laid over an existing roof does not qualify, so a Class 4 upgrade belongs on a tear-off; the roof-over vs tear-off guide covers what a second layer gives up.
What State Farm does not publish is the amount. Its pages say a qualifying roof may be eligible and that the reduction depends on your state; GAF’s own impact-resistance page says discounts are not guaranteed and vary by state and company. No carrier document we could read states a Wisconsin percentage, so the number comes from your agent, on your policy, before you sign. Ask one more question, because the State Farm form has a Class 3 box beside the Class 4 box and Farmers lists shingles approved by UL among its discounts: what does your standard Class 3 shingle earn, and what does Class 4 add? Only your agent knows.
When the extra cost for Class 4 shingles pays, and when it does not
The asphalt page prices a typical two-story house at $11,000 to $16,000 in standard architectural shingles. The Class 4 sibling goes on the same way on most roofs, so the premium is mostly material: field shingle, matching Class 4 ridge cap, and for GAF the accessories its wind warranty requires. The figures on that premium are IBHS’s: a cost survey across seven US markets, from around 2020, found shingles with its Good or Excellent ratings cost about 9% more per square, the 100 square feet roofers price by, with wide swings by region; its FORTIFIED home program puts the upgrade at $1,000 to $3,000 more on a 2,000 square foot roof. That is the number to earn back, and we quote both options on the estimate.
Two things pay it back. The credit is the predictable one once quoted: the annual difference times the years you will own the house. The other is the claim you may not have to file. Some Wisconsin policies carry a separate wind and hail deductible, flat or a percentage of dwelling coverage; find yours. A Class 4 roof that takes an inch-and-a-half to two-inch storm without cracking through is what keeps you from paying it. Nothing rates the roof for a repeat of Altoona.
The standard shingle is the right call when your agent quotes no credit and you expect to sell inside a few years, and when the budget is stretched, because the tear-off, ice barrier, and ventilation correction do more for the roof’s 25 to 30 years than the rating does; add the rating last.
Does the Class 4 credit come with a cosmetic hail damage exclusion in Wisconsin?
In every State Farm document we read, the cosmetic-damage exclusion is a metal-roof condition: the credit on a metal roof requires a signed endorsement excluding cosmetic hail loss, and you can decline the credit to keep the coverage. None attaches that endorsement to a Class 4 asphalt credit, so the trade the metal section of the hail versus wind damage guide describes is not the one you make here.
A cosmetic exclusion can be written for asphalt, though. A sample endorsement filed with Wisconsin’s Office of the Commissioner of Insurance in November 2023 defines cosmetic damage as damage to appearance but not function, excludes wind and hail loss that is solely cosmetic, and says granule loss on asphalt shingles is cosmetic as long as the shingles still keep water out. That is one insurer’s form rather than a state rule. A Class 4 rating is judged from the back, where the cracks are, and a cosmetic exclusion from the top, where the granule loss is; a shingle that passes the first and shows the second is the roof such an endorsement is written for. So read the endorsement that comes with any credit; the adjuster’s test square works the same on a Class 4 roof as on any other.